Polystyrene photographic element having a resinous terpolymer chromic chloride undercoat



' styrene sheeting and, accordingly,

can: F. Smith and Walter R. White, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester,

N. Y., a'corporation of New Jersey I Application February 14, 1958, Serial No. 715,296 sciaims. or. 96-87) This invention relates to polystyrene sheeting and more particularly to an improved oriented polystyrene film base having a resinous undercoat containing a chromium salt and a second coating or overcoat of a mixed gelatin and cellulose nitrate composition, which adhere firmly to the base andeach other and permit firm adherence thereto of a further coating thereover of a light-sensitive composi tion, preferably a gelatino-silver halide emulsionlayer, to give a photographic element of greatly improved dimensional stability.

It is known that various synthetic resins adhere to polycan be used as subbing compositions over which is coated a light-sensitive gelatin emulsion layer. One of the most satisfactory resins, insofar as. adhesion to the polystyrene is concerned, is polyn-butyl. methacrylate. However, a serious drawback to the use of this resinous material is that its softness permits the emulsion layer, under conditions of low humidity, to contractand shrink back from the edge of the film. This defect known as skidding may be eliminated for the most part by hardening the poly-n-butyl methacrylate by incorporating into the coating composition thereof certain harder resins having higher softening points or cellulose nitrate, which are compatible therewith. Too much of the hardening material will, of course, cause separation of the resin subbing layer from the polystyrene sheet. However, even when a proper amount of the harder resins are added to the poly-n-butyl methacrylate, it has been ob.- served that after some time, varying from a few days to a few months, aphotographic element using such a subbing layer may show a lifting of the emulsion around the edges of the support oralong scribed lines. This is a dc:

- n d States a n oided. disadvantage in graphic arts and cartographic processes.

We have now found that a greatly improved photo- 'graphicelementthat shows firm adherence of the emul sibn layer to a polystyrene film base, and more particularl'y-to an oriented polystyrene filmbase, under the usual conditions of processing and use, may be prepared by using a resinous terpolymer consisting predominantly of n-butyl methacrylate units and lesser amounts of methyl methacrylate andmethacrylic acid units in admixturewith a chromium salt, and more particularly chromic chloride, in the proportions of from 95-99% of the resinous terpolymer and from 5-l% of the said salt as the undercoat. layer. A mixed gelatin-cellulose nitrate overcoat is applied over the undercoat. This combination on photographic elements coated with a gelatino-silver halide emulsion gave photographic elements which showed good adhesion of the layers and the emulsion layer showed no tendency of edge lifting under testing and use conditions.

It is, accordingly, an object of the invention to provide subbing composition which adheres firmly to polybing composition, and a gelatino-silver halide emulsion coated over the subbed surface. Another object is to provide a process for preparin and photographic element. parent hereinafter. r

In accordance with theinvention, we prepare the improved photographic element-by coating one or both surfaces of oriented polystyrene film. base with a subbing composition termed the undercoat, typical compositions coming, within the: following generalformulation given inweightpercent: i

Other objects will become ap- Weight percent, of total In the above formulation, the proportion of n-butyl methacrylate units in the terpolyrner, is critical for if the amount is reduced below the lower limit to permit the presence of larger amounts of the harderunits, i. e the methyl methacrylate and methacrylic acid' units, poor adhesion to the polystyrene film base will result. On the other hand, if the proportion is increased above the upper limit, adhesidn will beimproved but skidding of the emul sion layer will become very bad. In the case of the methacrylic acid less than 2% of these units in the terpolyer permits undesired skidding, of 'the emulsion layer, while above 10% of these units the adhesion to'the poly styrene film base beginsto decrease sharply. The resinous terpolymer may be prepared by well known polymerika tion techniques employing the monomers in about the proportions found in the terpolymer, using heat and a peroxide polymerization catalyst. The amount of chromic chloride shown in the formulation is based f on the. weight of terpolymer used, i. e. 0.5-10%. It is ordinarily added in the form of the hydrate CrCl 6H' O. and functions primarily to eliminate dry edge lifting defe'ct. Any amount below or above this rangecauses poor adhesion between the second coating comprising a mixed gelatin-cellulose nitratesubbing. composition and the under coat. c c v After the undercoat has dried, a second subbingcomposition comprising a mixed gelatin-cellulosenitrate is applied over the above described undercoat layers. Typistyrene sheeting, and also firmly anchors light-sensitive gelatin emulsion layers to the subbed sheeting. Another object is to provide an improved photographic element comprising a film base of polystyrene, preferably oriented polystyrene film base,

a substratumof the aforesaid subpal. compositions of this kind that are useful are those which come within the following general formulation given in weight percent:

Weight percent of total Ingredient: of l00% Gelatin 0.6"-1.7 5 Acid dispersingagent for the gelatin 0.06-0.15 Cellulose nitrate 0.1 0.8 Acetone I20 --50- Methyl Cellosolve (ethylene glycol".

monomethyl ether); 5-15 Water 1 3.5 Methyl alcohol 30-75 Total r00 lnthe above formulation, the acid dispersing agent may beany bfthe conventionaraeias used for dispersing gelatin, e. g. acetic acid. Itmay vary over a moderately wide range, but preferably about 10% based on the weight of g the above subbed sheeting;

the gelatin.- The cellulose nitrate is preferably a low viscosity type having a nitrogen content of about 11% and being 80-90% soluble in alcohol. The amount of cellulose nitrate is dependent on the amount of gelatin varying from about 17-46%, based on the weight of the gelatin to give coated layer consisting essentially of from 68-86% by weight of gelatin and 32-14% by weight of cellulose nitrate. The amount of water is also determined on the gelatin content and is present approximately from 2 to 3 times the weight of the gelatin.

When the second subbing layer has dried, an ordinary gelatino-silver halide emulsion is coated thereover and dried. To eliminate any tendency to curl, the other subbed surface is overcoated with a gelatin composition containing no silver halide, but which may contain, if

desired, antistatic agents, filter dyes, and the like. The

photographic elements produced as above described were 4 On drying, a clear subbed film base was obtained. This I was then coated with a gelatino-silver halide emulsion characterized by firm adherence of the layers to one another and showed excellent dimensional stability under testing, use and storage conditions.

Representative subbed polystyrene sheeting and photographic elements prepared therewith are shown in cross section in the accompanying drawings illustrating the invention. 1 Referring to the drawings Fig. 1 illustrates an oriented polystyrene film base 10 having a mixed resinous terpolymer and chromic chloride undercoat layer 11 and an overcoat layer 12 of gelatin and cellulose nitrate.

Fig. 2 shows an oriented polystyrene film base 10 having a mixed resinous terpolymer and chromic chloride undercoat 11 on each side and an overcoat of mixed gelatin and cellulose nitrate layer 12 over each undercoat layer 11.

Fig. 3 shows an oriented polystyrene film base 10, having a mixed resinous terpolymer and chromic chloride undercoat layer 11 on each side,an overcoat of mixed gelatin and cellulose nitrate layer 12 over each undercoat layer 11, and a gelatino-silver halide emulsion layer 13 over an overcoat layer 12 and a gelatin layer 14 containing no silver halide over the other overcoat layer 12.

The invention is further illustrated by the following example:

Example An oriented polystyrene film base was coated on both sides with the following undercoat composition given in weight percent:

' Weight percent of total When the undercoatings had dried to give a clear subbed film base, an overcoating composition was applied over the undercoats. It had the following composition given in weight percent: 7

on one side, and with a plain aqueous gelatin solution on the other side. The dried photographic film element thus obtained was exposed and processed under standard testing conditions to a negative having sharp definition of the image. It showed no curl on drying and no dry edge lifting even after storage for several months. Scribed lines also were reproduced sharply in the prints made from the scribed negative. Accordingly, the photographic element of this example was found to be a highly satisfactory material for .use ingraphic arts and cartographic processes.

By following the procedure described in the preceding example, generally similar results were obtained with the other subbing composition of the'invention coming within the ranges of ingredients previously set forth. While the subbed styrene sheeting is intended primarily as a base material for the preparation of photographic elements, imbibition blanks, etc. it can also be used for non-sensitized gelatin coatings, e. g. for tapes of various kinds. Such materials may also contain dyes, pigments, and the like for certain desired effects.

What we claim is: p

1. A coating composition consisting essentially of from 2-6% by weight of a resinous terpolymer consisting of -88% by weight of n-butyl methacrylate units, 10- 40% by weight of methyl methacrylate units and 2-10% by weight of methacrylate acid units, 15-25% by weight of acetone, 70-85% by Weight of isopropyl alcohol and 0.0l0.60% by weight of chromic chloride.

2. A coating composition consisting essentially of 4% by Weight of a resinous terpolymer consisting of 76% by weight of n-butylmethacrylate, 19% by weight of methyl methacrylate and 5% by Weight of methacrylic acid, 20% by weight of acetone, 75.9% by weight of isopropyl alcohol and 0.1% by weight of chromic chlo ride.

3. An oriented polystyrene film base having on at least one side adjacent to said base an undercoat layer consisting essentially of a resinous terpolymer consisting of 50- 88% by weight of n-butyl methacrylate units, 10-40% by weight of methyl methacrylate units and 2-10% by weight of methacrylic acid units, and containing 0.5- 10.0% of chromic chloride, based on the weight of said terpolymer, and having an overcoat layer directly over at least one of said undercoat layers. consisting essentially of 68-86% by weight of gelatin and 32-14% by Weight percent of total.

Ingredient: of

Gelatin 1.25 Acetic acid -1 0.15 Cellulose nitrate (19.3% based on combined weight of gelatin and cellulose nitrate) 0.30 Acetone 20.0 Methyl Cellosolve 10.0 Water 2.5 Methyl alcohol 65.8

Total 100 weight of cellulose nitrate.

4. An oriented polystyrene film base having on at least one side adjacent to said base an undercoat layer consisting essentially of a resinous terpolymer consisting of 76% by weight .of n-butyl methacrylate units, 19% by weight of methyl methacrylate units and 5% by weight of methacrylic acid units, and containing 2.5% of chromic chloride based on the weight of the said terpolymer,

and having an overcoat layer directly over at least one of said undercoat layers consisting essentially of 80.7%

by weight of gelatin and 19.3% by weight of cellulose nitrate.

5. A photographic element comprising an oriented polystyrene film base, an undercoatlayer onboth sides adjacent to said base consisting essentially of a resinous terpolymer consisting of 50-80% by weight of n-butyl methacrylate units, 10-40% by weight of methyl methacrylate units and 210% by weight of methacrylic acid units, and containing 0.5-l0.0% by weight of chromic chloride based on the weight of said terpolymer, an overcoat layer directly over each of said undercoat layers consisting essentially of 68-86% by weight of gelatin and 32-14% by weight of cellulose nitrate, a gelatino-silver halide emulsion layer directly over one of said overcoat layers, and a layer consisting essentially of gelatin and devoid of any silver halide directly over the other of said overcoat layers. r

6. A photographic element comprising an oriented polystyrene film base, an undercoat layer on both sides adjacent to said base consisting essentially of a resinous terpolymer consisting of 76% by weight of n-butyl methacrylate units, 19% by Weight of methyl methacrylate units and 5% by weight of methacrylic acid units, and containing 2.5% of chromic chloride based on the weight of said terpolymer, an overcoat layer directly over each of said undercoat layers consisting essentially of 80.7% by weight of gelatin and 19.3% by weight of cellulose nitrate, a gelatino-silver halide emulsion layer directly over one of said overcoat layers, and a layer consisting essentially of gelatin and devoid of any silver halide directly over the other of said overcoat layers.

7. A process for preparing a photographic element comprising coating an oriented polystyrene film base with an undercoat composition consisting essentially of 26% by weight of a resinous terpolymer consisting of 50-80% by weight of n-butyl methacrylate units, -40% by weight of methyl rncthacrylate units and 2-10% by weight of methacrylic acid units, -25% by weight of acetone, 70-85% by weight of isopropyl alcohol and 0.01-0.60% by weight of chromic chloride to form undercoat layers adjacent to each side of said base, applying an overcoat composition directly over each of the said undercoat layers consisting essentially of 0.6-1.75% by weight of gelatin, 0.06-0.15% by weight of cellulose nitrate, 0.060.15% by weight of an acid disparsing agent for the said gelatin, 50% by weight of acetone, 545% by weight of ethylene glycol monomethyl ether, 1-3.5% by weight of water and -75% by weight of methyl alcohol to form overcoat layers, and applying a gelatino-silver halide emulsion over one of said overcoated layers, and over the other of said overcoat layers a composition consisting essentially of gelatin and water and being devoid of any silver halide.

8. A process for preparing a photographic element comprising coating an oriented polystyrene film base with an undercoat composition consisting essentially of 4% by Weight of a resinous terpolymer consisting of 76% by weight of n-butyl methacrylate units, 19% by weight of methyl methacrylate units and 5% by weight of methacrylic acid units, 20% by weight of acetone, 75.9% by weight of isopropyl alcohol and 0.1% by weight of chromic chloride to form undercoat layers adjacent to each side of said base applying an overcoat composition directly over each of said undercoat layers consisting essentially of 1.25% by weight of gelatin,

0.3% by weight of cellulose nitrate, 0.15% by weight of acetic acid, 20% by Weight of of ethylene glycol and 65.8% by weight of methyl alcohol to form overcoat layers, and applying a gelatino-silver halide emulsion over one of said overcoated layers, and over the other of said overcoat layers a composition consisting essentially of gelatin and water and being devoid of any silver halide.

No references cited,

acetone, 10% by Weight monomethyl ether, 2.5% of water 

5. A PHOTOGRAPHIC ELEMENT COMPRISING AN ORIENTED POLYSTYRENE FILM BASE, AN UNDERCOAT LAYER ON BOTH SIDES ADJACENT TO SAID BASE CONSISTING ESSENTIALLY OF A RESINOUS TERPOLYMER CONSISTING OF 50-80% BY WEIGHT OF N-BUTYL METHACRYLATE UNITS, 10-40% BY WEIGHT OF METHYAL METHACRYLATE UNITS AND 2-10.0% BY WEIGHT OF METHACRYLIC ACID UNITS, AND CONTAINING 0.5-10.0% BY WEIGHT OF CHROMIC CHLORIDE BASED ON THE WEIGHT OF SAID TERPOLYMER, AN OVERCOAT LAYER DIRECTLY OVER EACH OF SAID UNDERCOAT LAYERS CONSISTING ESSENTIALLY OF 68-86% BY WEIGHT OF GELATIN AND 32-14% BY WEIGHT OF-CELLULOSE NITRATE, A GELATIN AND HALIDE EMULSION LAYER DIRECTLY OVER ONE OF SAID OVERCOAT LAYERS, AND A LAYER CONSISTING ESSENTIALLY OF GELATIN AND DEVOID OF ANY SILVER HALIDE DIRECTLY OVER THE OTHER SAID OVERCOAT LAYERS. 